Vaporizer-type liquid fuel burning apparatus and electrical ingition means therefor



N v- 9, 1954 M. RESEK ETAL VAPORIZER-TYP 2,693,849 E LIQUID FUEL BURNINGAPPARATUS AND ELECTRICAL IGNITION MEANS THEREFOR 2 Sheets-Sheet 1 FiledJune 16. 1950 TIA 5 w W. w m mm m mfimv m A fin 5w "V. M

Nov. 9, 1954 M. RESEK ETAL 2,693,349 VAPORIZER-TYPE LIQUID FUEL BURNINGAPPARATUS AND ELECTRICAL IGNITION MEANS THEREFOR Filed June 16, 1950 2Sheets-Sheet 2 z M IIIge ENTORS dI'L' 531? 74 I 12 M'lburzfl. dcliolz 15Fe. 4 wwf-vmm struction that facilitates United States Patent APQRIZER TPE L QUID F UEL BURNING APPA- TUS AND ELECTRICAL IGNITION MEANS THEREFORMarc Resek, Cleveland Heights, Wilbur A. wood, and Lloyd V. Anti,Cleveland, to Perfection Stove Company, poration of Ohio ApplicationJune .1 1950, Serial N0. 168,524 3, Claims. (Cl. 158-91) This inventionrelates, generally, to the liquid fuel burner art; and it has to do moreparticularly with improvements in pot type vaporizing burners (asdistinguished from those of the pressure atomizing gun type) andespecially as such vaporizing burners are equipped with electricaligniters and are adapted for use with electrical control systems bywhich their operation is, rend rc autom ti vaporizing burners of theaforesaid type have several advantages over pressure atomizing burnersamong which are; multi-stag (high fire and low fire) operation affordingeven heat regardless of fluctuations in outside temperature and changingweather conditions; capability of operating with high efficiency andwith uniform temperatrue at low heat output when installed, for example,in small heating plants; absence of combustion and pump noises thatattend operation of pressure atomizing burners, and few mechanical Partsto wear or require service. Heretofore, however, these advantages havebeen offset in large measure by the inability to use, in vaporizingburners, the heavier types of fuel, especially if the fuel containslarge percentages of catalytic cracked stock.

It is the fundamental purpose of our invention to provid a vaporizingpot type burner which will operate in a highly satisfactory manner onvarious grades of oil that. are now in general use, including thosecontaining large percentages of cracked material.

Other objects of the invention are to provide a vaporizing pot typeburner that is capable of being readily controlled throughout its rangeof multi-stage operation, that functions satisfactorily at all stages,and that operates quietly and with high efficiency and with a clean fireat the different stages; to eliminate the disadvantages of priorvaporizing and pressure atomizing burners while retaining the advantagesof both types; to provide a conassembly and disassembly of, andaccessibility to, the parts which may require service and attention, andto provide a burner of the aforesaid character that is very durable andrequires the minimum of service and attention.

Another object of the invention is to provide a liquid fuel burner ofthe. vaporizing Pot type wherein the nozzle that delivers fuel to theburner pot is exterior of the com bustion space thereof; to include insuch burner provisions for maintaining the nozzle relatively cool, andto so relate the nozzle to the, surrounding parts that define the fuelentrance as to insure against fuel contact with or deposi Upon suchparts.

Further objects are to avoid, in vaporizing burners of the pot type,carbon formation at. the fuel inlet to the burner; the building up ofcarbon on the bottom of the burner pot, and the formation of carbon onthe electrical niter.

A still further and very important object of the inven-. tion is toprovide, in burners of the class to which our improvements pertain, anelectrical igniter of the enclosed, embedded variety. Heretofore, inburners of the Class at hand, either spark gap igniters, or igniters ofexposed resistance wir have been employed, These are subject to shortcircuiting by carbon deposit, and rapid deterioration because ofexposure to the high temperaures of combustion during burner operation.

In an electrical igniter of the kind herein disclosed, the current.carrying element or wire is embedded. in retract tory insulatingmaterial of high heat conductivity encased in a tube, of heat resistantmetal, substantially like the sheathed wire electrical heating. nitsemployed in elec- Sc hultz, Lake- Ohio, assignors Cleveland, Ohio, acoropening 35, and welded 2,693,849 Patented Nov. 9, 1954 tric ranges.Because the current carrying element or wire is completely insulated andsheathed from the fuel and vapor containing space of the burner there isno chance of short circuit or deterioration of the said element or wire.The metallic sheath also supports and protects the current carryingelement or wire from injury due to mechanical shock, and, furthermore,permits the use of a high resistance element to which the regular volthouse potential can be applied, whereby the need for an ignitiontransformer is eliminated.

An additional and related object of the invention is to combine with anelectrical igniter of the character described a bafile-like memberagainst which the fuel impinges and by means of which flow is retardedin the immediate vicinity of the igniter so as to insurerapidvaporization and ignition. More specifically, we employ a baffle-likemember in the form of an open ,end tray which, together with theigniter, is suspended within the burner pot at an elevation slightlyabove the maximum attainable fuel level in said pot. It will becomeapparent as this description proceeds that we have provided anigniterthat at all times is removed from any accumulation of liquid fuel withinthe burner.

The objects and advantages above enumerated, with others that willappear as this description proceeds, are attained in the embodiment ofthe invention illustrated in the accompanying drawings, wherein likereference characters designate like parts in the several views.

In the drawings, Fig. 1 represents a sectional side elevation of liquidfuel burning apparatus embodying our improvements, the view including adiagram of the electrical control system; Fig. 2 is a vertical sectionthrough the front portion of the burner, drawn to a scale considerablyenlarged over that of Fig. 1; Figs. 3 and 4 are sections on therespective lines 33 and 4-4 of Fig. 2, and Fig. 5 is a fragmentaryperspective view of the nozzle guide.

The liquid fuel burning'apparatus includes a burner pot or bowl that isdesignated, generally, by the reference numeral 1; an air housing,similarly designated 2, and a casing 3, shown in broken lines, thatencloses a combustion space or chamber C. The burner pot includes aperforated cylindrical peripheral wall 5 and a slightly dished circularbottom wall 6, the latter being shown in the present instance as formedintegral with the peripheral wall. Attached to the exterior of the potat about the junction of the walls 5 and 6 is a continuous annularoverflow trough 8 which communicates with the interior of the potthrough the lowest row of perforations, designated 10. The Wall 5 isprovided with a relatively large opening 12, and secured to the wallabout said opening, preferably by welding, is the inner end of acylindrical neck 15 that terminates at its outer end in a flange 16.

Welded or otherwise secured to the outwardly flared upper end of theperipheral wall 5 of the burner pot 1 is a generally upwardly convergentangular top wall 18, and shown as likewise secured to the edge portionof said top wall about the relatively large opening therein is the baseflange of a perforated neck 20. This neck is shown as flared outwardlyand thence upwardly to provide a peripheral flange that is secured to anupstanding flange of a ring-like member 23. Toward its outer edge saidmember is stepped abruptly upwardly, to provide a vertical cylindricalshoulder 24, outwardly I beyond which the member is provided with abroad flat flange 25 that is adapted to be engeged with the underside ofan annular bottom wall 28 of the casing 3, and to be detachably securedthereto by fastening means of bolts 29.

The air housing 2 includes a cylindrical peripheral wall 30, and acircular bottom Wall 31, formed to fit a suitable distance within thelower end of the peripheral wall. These walls are suitably securedtogether, by welding or other means, and attached to the upper end ofthe peripheral wall is a top member 32, shown as extending inwardly andthence upwardly, and as fitted to the shoulder 24 of. the previouslydescribe ringdike member 23.. th parts being f stened. together,vpreferably by welding. Opposite the neck 15 f h bumel? not, the wall 30is provided. with a lar or otherwise secured to said wall about theopening is the inner end of a sleeve 36. A suitable distance from itsouter end, the sleeve 36 18 provided with an internal flange 38 formed,in the present instance, of an annular member that is L-shaped in crosssection and a cylindrical portion of which is welded or otherwisesecured to the sleeve.

We shall next describe the means for delivering liquid fuel to theburner pot, and the electrical igniter by which the fuel is initiallyvaporized and ignited.

Attached, by screws or suitable fastening means 40 to the flange 16 ofthe neck 15, are the peripheral portions of circular plates 42 and 44,with a gasket 45 of packlng material interposed between the latter plateand said flange 16. By reason of their function, these plates will bereferred to, respectively, as the nozzle plate, and the igniter plate.These plates are provided with relatively large registering openings,and shown as fitted within the opening of the nozzle plate 42 is theouter open end of a cup-like shell 50, which we shall refer to as theouter shell, the shell and plate being secured together, desirably bywelding. 52 denotes a nozzle guide. It consists of a cylindrical bodythat is reduced in diameter adjacent its lower end and said end occupiesa circular opening in the lower side of the shell 50, the parts beingwelded or otherwise rigidly connected together. The nozzle guide 52 hasan axial passage enlarged at its upper end to provide an annularshoulder or seat 53; and a distance below said shoulder the passage isdownwardly convergent. 55 denotes an inner shell that is provided with aside opening that receives the bottom portion of the larger end of thenozzle guide 52. The inner shell is also welded or otherwise firmlysecured to the nozzle guide in spaced, substantially concentric relationto the outer shell 50.

Removably nested within the upper end of the nozzle guide is therelatively deep disc-like part or flange 57 of a fuel nozzle 58, thetubular tip of which depends axially from said flange and terminates atits lower end in a frusto-conical portion that is disposed in spacedsubstantially concentric relation to the tapered wall of the passage ofthe nozzle guide 52. Opening into the upper end of said passage are aplurality of air holes 59 of the nozzle flange 57, the portion of theflange outwardly of said holes resting upon the shoulder or seat 53. Thenozzle is provided with an axial port 60 that is counterbored andthreaded at its upper end for the reception of one end of an elbow 62,to the opposite end of which is communicatively connected. by aconventional coupling 63, the adjacent end of a fuel supply pipe 65.Above its frusto-conical portion, the nozzle 58 is bored transversely toprovide lateral openings 67 and below said o enings the nozzle istransversely slotted, thus imparting a bill-like appearance to the loweror fuel discharge end of the nozzle. By so forming the nozzle, itaffords better fuel discharge or dripping characteristics at any rate offuel feed. and insures ample volume at a high rate of flow. Furthermore.it so directs the fuel as to prevent contact of the fuel with the nozzleguide, this being highly important as otherwise residue and carbon wouldcollect and build up about the fuel inlet of the burner, due to the hightemperatures prevai ing within the latter during burner operation.

70 denotes an electrical i niter of the embedded sheathed type,previously described, and it is desirably in the form of a coil havingterminal portions that extend through aligned holes in the plates 42 and44. and are welded to the latter or igniter plate. Forwardly of saidplate. the terminal portions of the igniter are provided with bindingposts 74 and 75. The coil of the igniter is preferably inclineddownwardly and inwardly from the terminal portions, that are normal tothe igniter plate, toward the bottom wall 6 of the burner pot. A sheetmetal baflle is applied to the coil of the igniter 70 and the same is inthe form of a relatively wide channel or tray including a bottom wall81, side walls 82 and a relatively steep inclined wall portion 83against which the fuel impinges as it drops from the nozzle 58. Thebaffle 80 is held in position on the coil 70 by lugs 84 that extendinwardly over the coil from the side walls 82, and by a lug 85 that isstruck upwardly from the bottom wall 81 ad acent the lower edge of thelatter and rises within the lower convolution of the coil. The inclinedwall portion 83 of the bafile 80 is disposed at such an angle as todivert any splash of the fuel away from the region of the 4 fueladmitting aperture and over or toward the coil of the igniter.

By the use of the aforesaid inclined wall portion or extension 83, theigniter 70 can be spaced laterally of and somewhat remote from the fuelinlet of the burner so as to minimize the amount of heat radiated fromthe igniter to the part of the structure immediately surrounding saidinlet during the ignition period, while, at the same time, fuel will bedelivered in proximity to the igniter '70 by the baflle 80. It will beobserved that the bottom wall 81 of said baflle 80 is inclineddownwardly and inwardly, as is the igniter coil, so that although fuelis brought into contact with the igniter coil. such fuel will notaccumulate in the vicinity of the igniter at any time. This feature,plus the fact that the igniter 70 and baffle 80 are always above thesurface of the fuel in the burner pot, assures against cooling of theigniter during the ignition period by the fuel.

Liquid fuel is supplied to the burner pot through a so-called constantlevel control valve, shown conventionally in Fig. l and designated 90.It consists of a receptacle to which the fuel is c nveyed from asuitable source (not shown) by a pipe 92, under the control of a valve93 that is closed by a float 94, wherewith it has the usual operativeconnections, when fuel rises within the receptacle a given distance.While these float controlled valves are reasonably reliable. they aresubject to leakage, and for that reason, as will presently appear, we donot rely upon this float control valve to positively shut off the flowof fuel to the burner. Also incorporated in the unit is a metering valve98 that reciprocates within a hollow boss that rises from the bottom ofthe receptacle and through which communicative connection is establishedbetween the interior of the receptacle and the reviously mentioned fuelsupply pipe 65. As revealed in Fig. l, the metering valve 98 consists ofa rod of a diameter to slidably fit within the previously mentionedhollow boss, and the rod has a slot in its lower end. Adiacent its upperend the rod has operative connection with a thermostat that is in theform of a bimetal strip, hereinafter to be described, and by means ofthis bimetal strip the valve is normally held at an elevation in whichthe sl t of the rod 98 extends a short distance above the top of theboss. Accordingly, when the metering valve is in normal position, alimited amount of fuel will be permitted to flow past the valve bygravity. Inc uded in the pipe 65 is a so-called fuel release valve 100of the well known solenoid operated type. The valve is biased towardclosed position and accordingly shuts off flow of fuel when the solenoidis deenergized. Reversely, so long as current flows through the coil ofthe solenoid, the valve will be held open. 102 denotes a similar inletvalve in the pape 92 which functions when the current is cut oif topositively arrest flow of fuel to the constant level control valve 90.As an emergency measure, so that the burner will operate on low fire incase of a general power failure, a by-pass 103 is provided in each ofthe pipes 65 and 92 about the valve 100 and 102 therein, each by-pass,in turn, being equipped with a manual valve 104.

Any liquid fuel that overflows, under abnormal conditions, from theburner pot 1 into the trough 8 is conveyed through a pipe 105 to aclosed vessel 106 from which a tube 107 rises through the bottom of thereceptacle of the constant level control valve and terminates thereinabove maximum liquid level. A float 110 operates within the vessel 106and a rod 111 rises from said float through the tube 107 and ismaintained by the latter with its upper end in vertical alignment with afinger 112 on the float 94. Accordingly, when overflow fuel risessufficiently within the vessel 106, the float 110 lifts the rod 111 soas to engage its upper end with the finger 112 and prevent the float 94from dropping and lifting the valve 92 from its seat. By this meansnormal feed of fuel to the burner is prevented until the vessel 106 isdrained by the opening of a valve 114 adjacent the bottom of the vessel106.

designates an air impeller or centrifugal blower that suppliescombustion air to the burner. The outlet of the casing of the airimpeller or blower 120 ,fits w thin a sleeve 122 that is carried by andextends through an opening in a disc or plate 125, and to which sa dsleeve is rigidly secured, as by welding. The d sc or plate 125 isflanged about its edge and fits within the outer end of the sleeve 36and against the previously. mentioned flange 38 to which it is securedby a plurality of fastening means 126. These fastening means may consistof screws that are engaged within threaded holes of said flange. Thedisc or plate 125 is provided with an aperture for the accommodation ofthe fuel supply pipe 65.

The electrical systemby which the operation of the burner isautomatically controlled (although constituting no part of the inventionthat forms the subject matter hereof) is shown in the diagram that formsa part of Fig. l, and it includes, besides the solenoids of the valves100 and 102, the following parts: a transformer 130, the primary andsecondary windings of which are designated 131 and 132, respectively; aroom thermostat 135 that is shown conventionally as comprising athermosensitive element of the bimetal variety 136 through which, and aleaf 137 that is carried thereby, current is adapted to be conducted tothe low fire contact 138, and the high fire contact 139; a so-calledMicro switch 140, the movable element 141 of which is biased in adirection to engage a contact 142, and which is moved into engagementwith a contact 143, through the intervention of a push rod 144, by aleaf spring 145. 150 designates, generally, a switch including blades151 and 152 that are mechanically connected by an extension 153 of thecore of a solenoid 155. A bimeta'l strip 158'has operative connectionwith the metering valve 98 and serves, when cold, to retain the valveopen sufficiently to pass enough fuel to maintain low fire burneroperation. Associated with said bimetal strip is an electric resistanceheater 160, and when this heater is energized it causes the bimetalstrip to warp in a direction to lift the metering valve to wide openposition, therebyto pass sufiicient fuel to maintain high fire operationof the burner. Associated with the previously mentioned leaf spring 145is a thermostatic element in the form of a bimetal strip, designated165. When this element or strip is cold it contacts the free end of theleaf spring 145 and holds the latter under tension in a position tomaintain, through the intervention of the push rod 144, the movableelement 141 of the Micro switch in engagement with the contact 143thereof. When heat is imparted to the element or strip 165 by anelectrical resistance heater 167, said element or strip will warp in adirection to relax the leaf spring 145 and thereafter withdraw from saidspring and engage a contact 168, the latter occurring after a suitableinterval of time. Relaxing of the spring 145 permits the movable element141 of the Micro switch 140 to snap over into engagement 170 designatesa so-called top limit switch, asafety feature usually employed indomestic furnaces and other similar apparatus, to open the controlcircuit in case the apparatus becomes overheated, such switch,obviously, being disposed in intimate suitable part of the apparatus.

The usual house circuit, furnishing electrical energy at a potential ofsay 110 volts, is represented by a conductor 175 that leads to theprimary winding 131 of the transformer 13!), and a conductor 176 thatleads from said winding. The circuits of higher potential or voltage areshown in heavy lines, and those of comparatively low voltage, in lightlines. The motor 180 of the air impeller or blower 120, and the igniter70, which may have a capacity of say 500 watts, are in high voltagecircuits, as will presently appear. Current is carried from theconductor 175, through a conductor designated 182, to the movableelement 141 of the Micro switch 140. The contact 143 of said switch isplaced in electrical connection with one side of the motor 180 through aconductor 183. The other contact 142 of said switch has electricalconnection with the terminal 75 of the igniter 70 through a conductor184. Current returns from the motor and igniter to the other side of thehigh voltage circuit through a conductor 185 and its respective branches186 and 187. The low voltage circuits, say of 24 volts. that have astheir source of current the secondary winding 132 of the transformer,will be described in connection with the operation of the apparatus.

As illustrated in Fig. 1, the apparatus is inactive excepting for theoperation of the air impeller or blower. it being assumed that thetemperature of the space to which the room thermostat 135 is subjectedis above that requiring immediate low fire operation. Upon decline ofsaid temperature to the upper limitof a temperature with the contact142. r

heat exchange relation to a 6 range for which the thermostat is set, andwhich may be referred to as the comfort range, the element 136 thereofwill swing in a direction and only far enough to engage the leaf 137with the contact 138. This will close a circuit (starting with thesecondary winding 132 of the transformer) through a conductor 190, thewinding of the solenoid of inlet valve 102, conductor 191, thebeforementioned parts of the room thermostat, and a conductor 192,including the limit switch 170, back to the source. This will result inthe opening of valve 102, insuring ample fuel supply to the constantlevel control valve 90. Current will also flow from the conductor 190through a conductor 195, the blade 152 of the switch 150 and a conductor197 to the electrical resistance heater 167 and thence, through aconductor 198, to the previously mentioned conductor 191 and back to thesource. Very shortly, or about ten seconds, after the energization ofthe heater 167, the element or strip 165 will warp enough to relax thespring and permit the movable element 141 of the micro switch 140 tosnap into engagement with the contact 142, whereupon current will flowthrough the conductor 184 to the igniter 70, returning through theconductors designated 187 and 185 to the negative side of the maincircuit. Withdrawal of the element 141 from 1 the contact 143 will, ofcourse, cut off the supply of current to the motor 180 of the airimpeller or blower, thus interrupting the air supply to the burnerduring the ignition phase and accordingly accelerating the preheating ofthe igniter and adjacent parts of the burner due to the absence of thecooling effect of the air. Until the element or strip 165 is warpedsufliciently to engage contact 168, the igniter 70 will continue tobuild up heat in itself and in the adjacent parts of the burner bowl.After an interval of time, say one and one-half minutes, said element orstrip 165 will engage the contact 168 and close a circuit including,besides said element and contact, conductors 200 and 201, the winding ofthe solenoid 155, and a conductor 202 that leads back to the previouslymentioned conductor 191. Upon energization of the solenoid 155, theblades 151 and 152 of the switch will be swung into engagement with therespective contacts 205 and 206, the latter blade 152 withdrawingfrom acontact 2117 that controls the previously described circuit includingthe electrical resistance heater 167, thereby opening said heatercircuit. By engagement of the blade 152 with the contact 206, a circuitis established from the beforementioned conductor 195, through the blade152, contact 206 and a conductor 208 that joins the previously mentionedconductor 201 thereby to insure continued flow of current to thesolenoid after the element or strip cools and withdraws from contact168. During the interval of time that represents the cooling off periodof the element or strip 165, approxiinately one and one-half minutes,which is measured from the time said strip withdraws from contact 168until it engages and deflects the spring 145, the igniter 70 will remainenergized. There is, however, an appreciable fraction of this time, sayten seconds, when electrical contact is made between the element orstrip 165 and said spring 145 before the latter yields enough to effectoperation of the micro switch. During this dwell cur- 'rent will flowthrough the conductor 210, the switch blade 151, contact 205, aconductor 212, the winding of the solenoid of the fuel release valve 100and a conductor 213 to the previously mentioned conductor 262 and thenceto the source, thus opening said valve to permit oil to flow, under thecontrol of the metering valve 98, from the fuel supply of the constantlevel control valve 90 to the burner. I

Now, with the igniter and adjacent parts of the burner, including thebafiie 80, highly heated, the liquid fuel that drops from the nozzle 58will impinge against the steeper inclined portion of the bottom wall 81and practically instantaneously flash into vapor and be ignited, suchfuel as remains liquid rapidly vaporizing as it flows over the bottomwall of said baflie 80, in contact with the igniter, or, if not beforereaching this point, from the bottom of the burner pot, suiiicient airbeing supplied through the perforations of the peripheral wall of thepot to support such combustion as now occurs.

By this time the continued movement of the element I or strip 165- willhave fully deflected the leaf spring 145 and, through the mediumof therod 144, operated the micro switch 140, causing the element 141 thereofto withdraw from the contact 142 and resume engagement with the contact143. This will cut ofi supply of current to the igniter and reestablishthe circuit through which current is delivered to the motor 180 of theair impeller or blower 120. Air will now be supplied to the burner,desirably under the control of a damper 220, shown as positioned withinthe discharge opening of the impeller or blower, and which may be set toprovide the proper amount of air to the burner to produce the bestresults. It will be observed that the discharge opening of the impelleror blower casing is so related to the shells 50 and 55 as to insure aircirculating through the space between the shells and about the nozzle.The constant flow of air will keep said shells and the nozzle and nozzleguide relatively cool, notwithstanding their proximity to the intenseheat within the burner pot. Part of the air entering the shell 55 willpass through the holes 59 of the nozzle about the nozzle tip and throughthe passage of the nozzle guide. This will have the effect of preventingcontact of the liquid fuel with the surrounding portion of the guide,which is important from the standpoint of keeping these parts clear ofresidue and carbon, as already pointed out, and, at the same time, ofproviding primary air in the vicinity of the i niter.

Under the now prevailing conditions fuel will continue to flow to theburner in proper amount to maintain low fire. In the event thetemperature of the space to which the room thermostat is subjected risesas a result of the low fire condition to a value beyond the upper limitof the comfort range for which the room thermostat is set, the element136 will swing toward the position shown in Fig. 1, withdrawing the leaf137 from the contact 138, thus opening all circuits and allowing theburner to resume the condition assumed at the beginning of thedescription of operation. On the other hand, should the temperature ofsaid space, notwithstanding low fire operation, drop below the comfortrange, the element 136 of the room thermostat will swing still furtherin its former direction, maintaining engagement of the leaf 137 with thecontact 136 and, at the same time, engaging its terminal portion withthe contact 139 thereby to close the circuit that branches off from thepreviously described circuit represented in part by the conductor 212and through which current is supplied to the solenoid of the fuelrelease valve 100. The present circuit includes a conductor 225 thatleads from the conductor 212 to the electrical resistance heater 160that is associated with the thermosensitive element or bimetal strip158. Continuing on from this heater, the current returns to the sourcethrough a conductor 226, contact 139, the element 136 ofthe roomthermostat, and the conductor 192 which, as previously mentioned,contains the limit switch When the heater 160 is energized, the elementor strip 158 will warp in a direction to move the metering valve 98 towide open position, under which circumstances fuel in sufficientquantity is delivered to the burner to maintain high fire. When, underthese circumstances, the temperature to which the room thermostat isexposed rises to somewhere within the comfort range, under whichconditions low fire operation is suiiicient, the element 136 willwithdraw from contact 139 and open the circuit including the heater 160,after which the element or strip 158 will cool and resume its formercondition to return the metering valve to the position shown in Fig. l.

The valves 100 and 102, when the solenoids thereof are deenergized,serve to positively shut off the flow of fuel to the burner therebyinsuring against fuel drip when the room thermostat is not calling forheat. However, when said thermostat is in either of its effectivepositions, said valves 100 and 102 are open, under which circumstancesthe fuel supply to the burner is regulated by the constant level controlvalve 90, which includes the metering valve 98.

By reason of the novel manner in which the liquid fuel is admitted tothe vaporizing and carbureting zone of our improved burner, carbonformation about or within the fuel inlet is entirely avoided. Thisresults in part from the fact that the fuel is maintained at relativelylow temperature (below 200 F.) until it is entirely clear of the inletpassages. Instantly upon reaching the burner it drops into the aforesaidzone where it quickly attains a temperature high enough to completelyvaporize it and to burn it without carbon formation. Furthermore, carbondoes not form on the bottom of the burner pot be cause of the rapidvaporization of the fuel due to the high 8 temperature that prevailswithin the burner. Incidentally, in this connection, it may be pointedout that the parts of the burner subjected to combustion temperaturesare made of material which will not deteriorate at the high temperaturesmaintained during operation.

Important advantages of our improved burner arise from use of thesheathed, embedded type of igniter, as distinguished from theconventional spark gap igniter, and the exposed hot rod or wire igniter,and from the latter when encased only in a coating of quartz or thelike. Either of these spark gap or exposed wire types of igniters willbe shorted by even small amounts of carbon, resulting in ignitionfailure and in deterioration or destruction of the ignition elements.Furthermore, with conventional electrical igniters, ignition is so slowor the zone of ignition so confined that a long time is required for theburner to reach full fire, resulting in a lengthy period of smokyoperation each time the burner is started, and lack of heat for sometime after heat is needed. Also, by reason of our improvements, no pilotburner is required. As generally known by those acquainted with the art,pilot burners cannot be kept hot enough to prevent formation of carbonwhen burning the heavier grades of oil. Our improved igniter providesenough heat to accomplish three things, namely: (1) preheat the burnerparts hot enough to vaporize the liquid fuel the instant the fuel entersthe burner; (2) heat the resultant mixture of vapor and air hot enoughto cause instant ignition, and (3) accelerate the heating of the metalparts of the burner so that the fuel vaporizes fast enough to produce aclean hot fire shortly after the oil is ignited.

Because the current carrying element of our improved igniter iscompletely insulated and sheathed from the fuel and vapor there is nochance of short circuit or deterioration of the element.

Having thus described our invention, what we claim is:

l. A liquid fuel vaporizing burner comprising a burner pot including aperipheral wall and a bottom wall, the peripheral wall of the burner potbeing provided with an opening, an open end shell projecting throughsaid opening into the pot and having its open end substantially sealedto said peripheral wall about the aforesaid opening, said shell havingan aperture in the bottom thereof, a nozzle guide having its lower endwithin the aperture and secured to the shell about the same, an innershell having an opening in its lower side wherein the nozzle guide isfitted, said inner shell being secured to said guide and supportedthereby in spaced relation to the first mentioned shell, said guidehaving a vertical passage, a nozzle nested within the guide and providedwith a fuel discharge tip located adjacent the bottom of said passagesubstantially centrally thereof, a fuel supply pipe having communicativeconnection with the nozzle, an air housing surrounding and enclosing theburner pot, and means for supplying air to said housing and so arrangedas to project a part of the air into said shells.

2. A liquid fuel vaporizing burner comprising a pot including aperforated peripheral wall and a bottom wall, the peripheral wall havinga relatively large opening, a neck surrounding said opening andextending outwardly from said wall, a nozzle plate disposed across andsecured to the outer end of the neck, said plate having a relativelylarge opening, an open end shell projecting inwardly through thelastmentioned opening and having its open end secured to the nozzle plateabout the opening therein, an aperture in the bottom of said shell, anozzle guide having its lower end within said aperture and secured tothe shell about the same, an inner shell having an aperture in its lowerside wherein the nozzle guide is fitted, said inner shell being securedto the guide and supported thereby in spaced relation to the firstmentioned shell, said guide having a vertical passage, a nozzle nestedwithin the guide and provided with a fuel discharge tip located adjacentthe bottom of said passage substantially centrally thereof, a fuelsupply pipe having communicative connection with the nozzle, an airhousing surrounding and enclosing the burner pot, and means forsupplying air to said housing and arranged to project a part of the airinto said shells.

3. In a liquid fuel vaporizing burner, a walled struc ture enclosing acarbureting chamber and provided with means for admitting air to thelatter, a high wattage electrical igniter comprising a resistanceelement embedded in insulating material encased in a tubular metallicsheath, the igniter being formed intermediate its ends to provide a coiland having itsend portions arranged in laterally spaced relation to eachother and extended outwardly through and secured to a wall of saidstructure so as to support said coil within said chamber in spacedrelation to the walls thereof and in a plane slightly inclined to thehorizontal, a baffle including bottom and side walls applied to theigniter so that said bottom wall underlies and is closely adjacent andsubstantially parallel to the aforesaid coil and so that the side wallsrise on opposite sides of the coil, the baffle including also a wallportion that is inclined upwardly from the high side of the bottom wallin obtuse angular relation thereto, holding means attaching the baffleto the igniter, means for delivering fuel to the chamber above the bafile in such relation to said wall portion as to impinge thereagainst, andmeans supplying electrical energy to said resistance element ofsufiicient potential to cause said element to impart to the sheath afuel igniting temperature.

References Cited in the file of this patent UNITED STATES PATENTS Numbere Da 974,795

Number 10 Name Date Johnson June 23, 1914 Grotenhuis July 12, 1927Meyers Oct. 23, 1928 Ravenor June 3, 1930 Haden July 26, 1932 Babb Aug.30, 1932 1935 Dalen Mar. 15, 1938 Unser Apr. 22, 1941 Holthouse June 16,1942 Breese et al. Apr. 18, 1944 Tate Feb. 27, 1945 De Lancey May 15,1945 Hotchkiss Oct. 2, 1945 Miller et al. Mar. 4, 1947 De Lancey July 8,1947 Resek et a1 Mar. 30, 1948 Tramontini Sept. 13, 1949 Fiedler Nov.15, 1949 Long Aug. 29, 1950 Little May 22, 1951 Chadwick et al. Oct. 21,1952 Budlane May 5, 1953

